Camera

ABSTRACT

A camera which can execute data communication with an attached accessory that can perform a data printing operation wherein data received from the camera is printed on a film surface comprises a release device for generating a release signal for starting a photographing operation, a transmission device for transmitting data to the accessory during a time interval from the end of a photographing operation to be beginning of a next photographing operation, and a control device for enabling the photographing operation after intervening data transmission by the transmission device when the accessory is to perform the data printing operation, and for enabling the photographing operation without intervening data transmission by the transmission device when the accessory is not to perform the data printing operation.

This is a division of application Ser. No. 521,562 filed May 10, 1990(now U.S. Pat. No. 5,001,503) which is a division of application Ser.No. 354,397 filed May 19, 1989 (now U.S. Pat. No. 4,942,413).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera, a data printing device (to bereferred to as a data back hereinafter) capable of being mounted on thecamera and of printing various data on a film loaded in the camera, anda film winding device assembled in the camera.

2. Related Background Art and Objects of the Invention

In a camera system in which a camera and a data back which does notcommunicate data with the camera are combined to perform a photographingoperation, the data back changes a data printing time in accordance witha data printing signal from the camera, a transmission time of whichchanges depending on a film sensitivity. In this system, since signalprocessing of the data back is not complicated, if the transmission timeof the data printing signal transmitted from the camera to the data backchanges, no problem is posed.

There is also known a camera system in which a camera and a data backwhich communicates data with the camera are combined to perform aphotographing operation. A camera system of this type which has variousfunctions realized by serial data communication between a camera and adata back is disclosed in Japanese Patent Laid-Open (Kokai) No.61-167934.

In this system, since signal processing of the data back is complicated,if the transmission time of the data printing signal transmitted fromthe camera to the data back changes, an erroneous operation may becaused by the change in transmission time.

It is a first object of the present invention to provide a camera whichcan prevent an erroneous operation when a camera and a data back whichdoes not communicate data with the camera are combined or when a cameraand a data back which communicates data with the camera are combined.

Certain, usually inexpensive, data backs having a data communicationfunction may also present a problem relating to frame speed. Such databacks typically employ a relatively low speed microcomputer operating onthe basis of oscillation at 32 kHz. By contrast, a microcomputer used ina camera requires high-speed processing, for which an oscillator of 4 to8 MHz is commonly employed. When data communication is to be performedbetween the microcomputers, the data communication speed must bedetermined in correspondence with the microcomputer having a lower datacommunication speed. Since a data communication time is about severaltens of ms (although it varies depending on the number of data), a framespeed tends to decrease, thus posing a problem. Of course, themicrocomputer of the data back may be operated at a clock of about 4 to8 MHz when the camera is activated, and may be operated at a clock ofabout 32 kHz when the camera is deactivated. However, in this case, thesystem becomes complicated, or an expensive microcomputer must be used.

It is therefore a second object of the present invention to provide acamera system in which an inexpensive data back, for example, canperform printing based on data received from a camera without adverselyaffecting frame speed.

Another significant problem associated with the use of data backs occurswhen a data back is combined with a conventional camera having anelectric winding device. Such a camera is designed to perform a filmwinding operation immediately after exposure of an object for a presentshutter time is completed. In order to avoid blurring of the dataprinted by the data back when the film is wound, the data printingoperation is interrupted when the exposure is completed, before the filmwinding operation is performed. This operating sequence, while avoidingblurring of the printed data, gives rise to another problem whenlow-sensitivity film is used. More particularly, because low-sensitivityfilm necessitates a long printing time, the print density obtained whenthe printing operation is interrupted is often insufficient for the datato be discriminated. This phenomenon becomes more pronounced withdecreasing shutter time and decreasing film sensitivity.

It is a third object of the present invention to solve this problem.

SUMMARY OF THE INVENTION

In order to achieve the aforementioned first object, a camera of thepresent invention which can receive an accessory for performing a dataprinting operation on a film surface and which can execute datacommunication with the accessory, includes:

(a) identification means for identifying whether or not thecommunication is attained between the camera and the accessory, and

(b) transmission means for transmitting a printing signal for causingthe accessory to start the data printing operation from the camera tothe accessory within a predetermined transmission time.

The transmission means changes the transmission time on the basis of theidentification result of the identification means.

In order to achieve the second aforementioned object, a camera of thepresent invention which can receive an accessory for performing a dataprinting operation on a film surface and which can execute datacommunication with the accessory, includes:

(a) release means for generating a release signal for starting aphotographing operation,

(b) transmission means for transmitting data to the accessory during atime interval from the end of the photographing operation to thebeginning of the next photographing operation, and

(c) control means which, when the accessory performs the data printingoperation, enables the photographing operation after intervening datacommunication and which, when the accessory does not perform the dataprinting operation, enables the photographing operation withoutintervening data communication.

In order to achieve the second object, an accessory of the presentinvention which is mountable on a camera having film frame count datacommunication capability, and which can print film frame count data on afilm surface, includes:

(a) detection means for detecting a photographing signal generated witheach photographing operation of the camera,

(b) data reception means for receiving the film frame count data of thecamera by communication with the camera, and

(c) storage means for storing film frame count data based on the filmframe count data received from the camera.

When the detection means detects the photographing signal, the storagemeans stores a value obtained by incrementing the presently stored filmframe count data by one frame, and when film frame count data from thecamera reception means receives the data, stores the received film framecount data in place of the presently stored frame count data.

In order to achieve the aforementioned third object, a film windingdevice of the present invention includes:

(a) first timer means for measuring a first time associated with a dataprinting operation,

(b) second timer means for measuring a second time associated with ashutter,

(c) logical sum means for receiving a signal output from the first andsecond timer means, discriminating whether or not both the first andsecond timer means output completion signals, and changing its output onthe basis of the discrimination result, and

(d) film winding means for detecting a change in output from the logicalsum means to start a film winding operation.

These and other objects and advantages of the present invention will beeasily understood from the following detailed description taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a combination of a camera and ahigh-performance data back according to a first embodiment of thepresent invention;

FIG. 2 is a flow chart of the main routine of an MCU 10;

FIG. 3 is a flow chart of a release interruption processing routine ofthe MCU 10;

FIG. 4 is a flow chart of a communication routine of the MCU 10;

FIG. 5A is a flow chart of the main routine of an MCU 21;

FIG. 5B is a flow chart of an interruption processing routine of the MCU21;

FIG. 6 is a flow chart of a communication routine of the MCU 21;

FIG. 7 is a flow chart of a printing routine of the MCU 21;

FIGS. 8A-G are a timing chart of communication between the camera andthe high-performance data back;

FIG. 9 is a timing chart in a release sequence when the camera iscombined with the high-performance data back;

FIGS. 10A and 10B are views for explaining contents of 4th and 5th bytesof communication data;

FIG. 11 is a block diagram showing a combination of the camera shown inFIG. 1 and a simplified data back;

FIG. 12 is a timing chart of communication between the camera and thesimplified data back;

FIG. 13 is a timing chart of a release sequence when the camera iscombined with the simplified data back; FIG. 14 is a flow chart of amain routine of an MCU 10 of a camera according to a second embodiment;

FIG. 15 is a flow chart of a release interruption routine of the MCU 10;

FIG. 16 is a flow chart of a communication routine of the MCU 10;

FIG. 17A is a flow chart of the main routine of an MCU 21 of a data backaccording to the second embodiment;

FIG. 17B is a flow chart of an interruption processing routine of theMCU 21;

FIG. 18 is a flow chart of a communication routine of the MCU 21;

FIG. 19 is a flow chart of a printing routine of the MCU 21;

FIGS. 20A-G are a timing chart of communication between the camera andthe data back;

FIGS. 21A and 21B are timing charts of a release sequence;

FIG. 22 is a view showing an outer appearence of a camera and a databack according to a third embodiment of the present invention;

FIG. 23 is a block diagram of pertinent portions of the camera and thedata back;

FIGS. 24A and 24B are timing charts illustrating operation of thearrangement of FIG. 23;

FIGS. 25A to 25E are flow charts according to a fourth embodiment of thepresent invention; and

FIG. 26 is a block diagram of the fourth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) First Embodiment

FIGS. 1 and 11 are block diagrams of a first embodiment of a camera andan accessory loaded on the camera.

In FIG. 1, a camera 1 receives a detachable accessory 20 (to be referredto as a data back hereinafter) of a high-performance type (i.e., a typecapable of communicating data with the camera) capable of printing data.The camera 1 has six contacts 1a to 1f, and the high-performance databack 20 has the same number of contacts 20a to 20f as that of thecamera. When the data back 20 is mounted on the camera 1, the contactshaving the same suffixes are connected to each other. A microcomputer(to be referred to as an MCU hereinafter) 10 A/D-converts an output froma known photometer 2 into a photometric output. An information-settingdevice 3 supplies information which can be externally set, e.g.,exposure control mode information, preset film sensitivity information,preset shutter speed information, or diaphragm information from aphotographing lens, to the MCU 10. A release switch SW1 is normally keptoff, and is turned on when a release button (not shown) is depressed. Adisplay 4 displays various exposure information in accordance with anoutput from the MCU 10. When the release button is depressed and therelease switch SW1 is turned on, after a predetermined calculation iscompleted, a sequence-activator 5 is activated by the MCU 10 to start arelease sequence. For example, a magnet in the activator 5 is energizedto start a mirror-up operation. A diaphragm controller 6 performsautomatic diaphragm control in a program exposure control mode or ashutter priority mode. A shutter-controller 7 controls shutter curtainsto attain a preset shutter speed or a shutter speed calculated by theMCU 10. A shutter-charge and film-feed device 8 performs a shuttercharge operation and winding and rewinding operations of a film after arelease operation. An E² PROM 9 stores necessary data such as dataassociated with a photographed film frame count after a power switch ofthe camera is turned off. The MCU 10 performs an apex calculation on thebasis of setting by the photometer 2 and the information-setting device3, and transmits a display output to the display 4. After the releaseoperation, the MCU 10 controls the sequence-activator 5, the diaphragmcontroller 6, the shutter-controller 7, the shutter-charge and film-feeddevice 8, the E² PROM 9, and the like.

When the release button is depressed and the release switch SW1 isturned on, the MCU 10 activates the sequence-activator 5 after itcompletes the apex calculation. The sequence-activator 5 starts amirror-up operation. After the sequence-activator 5 is activated, theMCU 10 activates the diaphragm controller 6. When a diaphragm prioritymode (to be referred to as an A mode hereinafter) or a manual exposuremode (to be referred to as an M mode hereinafter) is set, the MCU 10need not generate a diaphragm stop signal, and control is made with adiaphragm value set by a diaphragm ring of a lens. On the other hand, ifa program exposure mode (to be referred to as a P mode hereinafter) or ashutter priority mode (to be referred to as an S mode hereinafter) isset, the diaphragm ring of the lens can be turned to a minimum diaphragmposition. In this case, the MCU 10 generates a stop signal when adiaphragm value calculated in accordance with the mode is reached, andthe diaphragm controller stops the diaphragm of the lens upon receptionof this signal. Subsequently, the MCU 10 activates theshutter-controller 7. The shutter-controller 7 starts traveling of afront curtain of the shutter. The shutter-controller 7 starts travelingof a rear curtain after the lapse of a time period corresponding to ashutter speed set by a user if the M mode is set or after the lapse of atime period corresponding to a shutter speed calculated by the MCU 10 ifthe P, S, or A mode is set.

The high-performance data back 20 comprises a microcomputer (MCU) 21, amode selector 22, an information-setting device 23, a display LCD 24, adata-printing LCD 25, and a printing lamp 26. Information set by themode selector 22 or the information-setting device 23 is input to theMCU 21, and the display LCD 24, the data-printing LCD 25, and theprinting lamp 26 are driven on the basis of signals from the MCU 21.

                  TABLE 1                                                         ______________________________________                                                                          Trans-                                                    Memory     Memory   mission                                                   of         of       direc-                                      Content       MCU 10     MCU 21   tion                                        ______________________________________                                        1st     Data back M (1)      DM (1) 1 ← 20                               byte    flag                                                                  2nd     Film      M (2)      DM (2) 1 → 20                             byte    sensitivity                                                           3rd     Film frame                                                                              M (3)      DM (3) 1 → 20                             byte    count                                                                 4th     Shutter   M (4)      DM (4) 1 → 20                             byte    speed                                                                         information                                                           5th     Diaphragm M (5)      DM (5) 1 → 20                             byte    information                                                           ______________________________________                                    

The camera 1 and the high-performance data back 20 exchange 5-byte datashown in Table 1. More specifically, after 1st-byte data is transmittedfrom the high-performance data back 20 to the camera 1, remainingfour-byte data are sequentially transmitted from the camera 1 to thehigh-performance data back 20. The MCU 10 and the MCU 21 have the samenumbers of communication memory areas M(1) to M(5) and DM(1) to DM(5),and these memory areas can be expressed as M(N) and DM(N) using a memorypointer N (=1 to 5).

                  TABLE 2                                                         ______________________________________                                        Bit    Flag name       Content of flag                                        ______________________________________                                        7                      Normally 1 as identifi-                                                       cation                                                 6                      Undefined (0)                                          5                      Undefined (0)                                          4                      Undefined (0)                                          3                      Undefined (0)                                          2                      Undefined (0)                                          1                      Undefined (0)                                          0      EXPF            1 when printing is                                                            performed                                              ______________________________________                                    

First-byte data is data back flag information which is transmitted fromthe high-performance data back 20 to the camera 1. The 1st-byte data hasa format defined as shown in Table 2. A bit "7" of this byte is a flagindicating that a data back can perform communication, and is always setto be 1 when communication can be performed. A flag EXPF of a bit "0" isset to be 1 when a state for printing an exposure value controlled bythe MCU 10 is set. Thus, data back flag information is set to be $80(10000000 in binary notation) or $81 (10000001 in binary notation) whenan undefined flag is fixed to be 0.

Second-byte data and subsequent data are sent from the camera 1 to thehigh-performance data back 20. The 2nd-byte data indicates a filmsensitivity, and is an SV value set at the camera 1 or read from a DXcode. 3rd-byte data indicates a photographed film frame count displayedon the camera 1. When the camera is empty (no film is loaded in thecamera), this data is determined to be $0E. 4th- and 5th-byte dataindicate shutter speed information and diaphragm information,respectively, and are determined to have the same formats as contentsdisplayed on the camera 1, as shown in FIGS. 10A and 10B.

FIG. 2 is a flow chart of the main routine of the MCU 10.

Step #0 is a preset routine executed immediately after the MCU 10 isreset, and various setting operations required immediately after, e.g.,release interruption is enabled are performed. A photometry routine isexecuted in step #1. A photometric output is received from thephotometer 2 and is A/D-converted, and the A/D-converted value isstored. In step #2, an information-setting routine is executed, so thatan exposure control mode, a DX code of a patrone, various information ofa lens, a preset shutter speed, and the like are read from the settingdevice 3. In step #3, an apex-calculating routine is executed. Anexposure calculation is performed on the basis of information read insteps #1 and #2, and a shutter speed and diaphragm value for display andcontrol are determined. In step #4, a display routine is executed todrive the display 4, thereby performing a predetermined display of,e.g., an exposure value. In step #5, a communication routine shown inFIG. 4 (to be described later) is called, and communication with thedata back is performed. In step #6, it is checked if the bit "7 " of1st-byte data M(1) is 1. If YES in step #6, the flow advances to step#8; otherwise, the flow advances to step #7. The flow advances to step#7 when it is determined that the high-performance data back 20 is notmounted (different from the case of FIG. 1). In step #7, a transmissiontime (tp) of a printing signal to a simplified data back shown in FIG.11 (i.e., a data back having no function of communication with a camera)is set according to a film sensitivity SV of a film loaded in thecamera. The time tp is set to be short when a high-sensitivity film isused, and set to be long when a low-sensitivity film is used. The flowadvances to step #8 when communication with the high-performance databack 20 is attained In step #8, the transmission time tp of the printingsignal is set to be 10 ms, regardless of the film sensitivity set at thecamera, and an actual data printing time is determined on the basis offilm sensitivity information separately transmitted from the camera tothe data back or film sensitivity information set at the data backitself. Thus, it will be appreciated that the printing signal for thesimplified data back instructs the data back to perform a data printingoperation, and controls an actual printing time, while the printingsignal for the high-performance data back simply instructs the data backto perform a data printing operation. When step #7 or #8 is completed,release interruption is enabled in step #9. After step #9, the flowreturns to step #1. Thereafter, a state wherein interruption is enabledis set.

When a release operation is performed after the interruption is enabled,the flow jumps from step #44 in an interruption processing routine shownin FIG. 3 (to be described later) to step #10 in FIG. 2. In step #10, astack is cleared. The state is changed so that processing can be startedfrom step #11 even in a state of any one of steps #1 to #9 describedabove. In step #11, a sequence-activating routine is executed toactivate the sequence-activator 5. The sequence-activator 5 is caused toenergize a magnet and the like, thus starting a mirror-up operation. Adiaphragm-controlling routine in step #12 is then executed. When thediaphragm of a lens is turned to a predetermined value position, adiaphragm stop magnet of the diaphragm controller 6 is energized to lockthe diaphragm. In step #13, a shutter-controlling routine is executed,so that the shutter-controller 7 controls to obtain a predeterminedshutter speed. In step #14, a mirror-down, shutter-charging, andfilm-feeding routine is executed, so that the shutter-charge andfilm-feed device 8 is operated. Upon completion of this operation, theflow returns to step # 1, i.e., again to the photometry routine afterthe mirror-down operation. The processing is then restarted from thephotometry routine in step #1.

FIG. 3 is a flow chart of the release interruption processing routine.After the interruption is enabled in step #9, this routine is executedupon interruption every predetermined period of time (e.g., every 2 ms)while the operations in steps #1 to #9 and #10 to #12 are executed Whenthis routine reaches a "return" step, the flow returns to processing inFIG. 2 before interruption processing. Immediately after power-on,interruption is forbidden, and after interruption is enabled in step #9,this routine can be executed.

When this routine is executed, it is checked in step #41 if a printingflag PRNF in a RAM of the MCU 10 is 0. The printing flag PRNF is set tobe 1 when the release operation is started upon depression of a shutterbutton, and is reset to be 0 after the lapse of a predetermined periodof time. This predetermined period of time is a transmission time. If itis determined in step #41 that the flag PRNF is 0, the flow advances tostep #42; and if it is determined that the flag PRNF is 1, the flowadvances to step #45. The printing flag PRNF is 0 before the releaseoperation is detected, and the flow advances to step #42. In step #42,it is checked if an input terminal P10 is set at L level upon an ONoperation of the release switch SW1. If YES in step #42, the flowadvances to step #43; otherwise, the flow returns to the main routine,and processing before the interruption processing is restarted. When therelease button is depressed and the release switch SW1 is turned on, theterminal P10 is set at L level, and the flow advances to step #43. Instep #43, a terminal P11 is set at L level to generate a printing signal(for instructing a data printing operation by the data back) to thehigh-performance data back 20. In step #44, the printing flag PRNF isset to be 1, and an internal timer of the MCU 10 is reset. This timermeasures the transmission time tp of the printing signal transmittedfrom the camera to the data back. After step #44, the flow jumps to step#10 in the main routine of FIG. 2, and the sequence-activating routinein step #11 is executed. When the interruption processing routine inFIG. 3 is executed during execution of step #11, since the printing flagPRNF is set to be 1 in step #44, as described above, the flow advancesfrom step #41 to step #45. In step #45, a value t of the above-mentionedtimer is compared with the predetermined transmission time tp. If thetime tp has passed, the flow advances to step #46; otherwise, the flowreturns to the main routine, and the processing in FIG. 2 before theinterruption processing is restarted. When the predeterminedtransmission time tp has passed, the flow advances from step #45 to step#46. In step #46, the printing signal terminal P11 is set at H level tostop transmission of the printing signal from the camera to the databack. In step #47, the flag PRNF is set to be 0. In step #48,interruption is forbidden, and the flow returns to the routine in FIG. 2prior to the interruption processing. Thereafter, the interruptionroutine in FIG. 3 is not executed until the interruption is enabledagain in step #9 in FIG. 2.

FIG. 4 is a flow chart of the communication routine of the MCU 10 whichis called as a subroutine in step #5 in FIG. 2.

In step #101, a terminal P12 is set at L level, and is again set at Hlevel after the lapse of a predetermined period of time. To set theterminal P12 at L level means generation of an activating signal forstarting data communication between the camera and a mounted data back.If the high-performance data back 20 is mounted, a terminal Q12 of theMCU 21 connected through the contacts 1b and 20b is set at L level inresponse to the activating signal. Even though the terminal P12 of theMCU 10 would otherwise to H level after the lapse of the predeterminedperiod of time as described above, it is kept at L level as long as theterminal Q12 of the MCU 21 is at L level.

In step #102, it is checked if an input to the terminal P12 is at Llevel. If it is determined in step #102 that the terminal P12 is at HLevel, the flow advances to step #106; otherwise, the flow advances tostep #103. If the high-performance data back 20 is mounted, since theterminal P12 is set at L level, the flow advances to step #103. If thehigh-performance data back 20 is not mounted, the terminal P12 is set atH level, and the flow advances to step #106. In step #106, the memoryM(1) for storing data back flag information is cleared. To check if theterminal P12 is set at L level is equivalent to check if a data backmounted on the camera 1 is a high-performance data back or a simplifieddata back.

As described above, processing after step #103 is executed only when thehigh-performance data back 20 is mounted. In steps #103 to #105,processing for receiving data back flag information of a 1st byte fromthe high-performance data back 20 is executed. In step #103,transmission of a serial clock from the camera 1 to the data back isstarted. In step #104, it is waited until a total of a time requireduntil transmission of the 1st-byte signal is completed and a timerequired until the MCU 21 of the data back is ready for receiving thefollowing 2nd-byte data elapses. In step #105, communication data(above-mentioned 1st-byte data) supplied from the high-performance databack 20 and stored in a serial register SR (not shown) of the MCU 10 isstored in the memory M(1) shown in Table 1 of the MCU 10 of the camera.

In steps #107 to #111, processing for transmitting 4-byte data (2nd to5th bytes) from the camera 1 to the high-performance data back 20 isexecuted. In step #107, N=2 is set as a memory pointer of transmissiondata. In step #108, data in a memory M(N) (film sensitivity of the2nd-byte data since N=2 is initially set) of the MCU 10 is transmittedto the serial register SR. In step #109, transmission of a serial clockfrom the camera to the data back is started. In step #110, the datastored in the serial register SR is transmitted to the MCU 21 of thedata back, and it is waited until a total of a time required until thetransmission is completed and a time required until the MCU 21 of thedata back is ready for receiving data of the following bytes (3rd to 5thbytes) elapses Subsequently, in step #111, the memory pointer N isincremented by 1. If the memory pointer exceeds 5, the flow returns tothe main routine, and the flow advances from step #5 to step #6 in FIG.2. If the memory pointer is equal to or smaller than 5, the flow returnsto step #108. Since N=3 after the 2nd-byte data is transmitted, the flowreturns to step #108, and processing in steps #108 to #111 is repeated.After 5th-byte data is transmitted, since N=6 in step #111, the flowreturns, thus completing the communication subroutine shown in FIG. 4.

FIG. 5A is a flow chart of the main routine of the MCU 21 stored in thehigh-performance data back 20. When the MCU 21 is reset by loading abattery in the data back, preset processing is performed in step #501.After the power switch of the camera 1 is turned off, processing insteps #502 to #508 is repeated. In step #502, an information-settingroutine is called, so that setting information of, e.g., setting of aprinting mode from the mode selector 22 is read, or data to be printedis corrected in accordance with information from the information-settingdevice 23.

In step #503, it is checked if the terminal Q12 is at L level. If YES instep #503, the flow advances to step #505; otherwise, the flow advancesto step #504. The terminal Q12 is set at L level only when the terminalP12 is set at L level and communication is started from the camera 1. Inthis case, the flow advances to step #505 to call a communicationroutine shown in FIG. 6, thus exchanging data with the camera 1. Ifcommunication is not started from the camera 1, the terminal Q12 is keptat H level, and the flow advances to step #504. In step #504, it ischecked if a terminal Q11 is at L level. If NO in step #504, the flowadvances to step #507. The terminal Q11 is set at L level when therelease operation is started in the camera 1 and the terminal P11 is setat L level to activate the printing operation. In this case, the MCU 21calls a printing routine shown in FIG. 7 in step #506, and performs apredetermined data printing operation. Step #507 is executed after steps#504 to #506, and a printing time tq for actually performing an exposurein accordance with a film sensitivity SVD is set. The printing time tqis set to be short when a high-sensitivity film is used, and is set tobe long when a low-sensitivity film is used. The film sensitivity SVD isnormally set according to the film sensitivity SV (=DM(2)) sent from thecamera 1 but does not always coincide with SV since the sensitivity SVis sometimes corrected in correspondence with a special-purpose film. Instep #508, data set in step #502, data obtained by communication in step#505, and data which is changed after the printing operation in step#506 are displayed. Upon completion of the processing in step #508, theflow returns to step #502, and the above-mentioned processing isrepeated.

FIG. 5B is a flow chart of an interruption routine of the MCU 21 storedin the high-performance data back 20. This routine is activated everyminute by an interruption of a timer incorporated in the MCU 21, andyear, month, day, hour, and minute data are counted up. When the flowreaches a "return" terminal, processing in FIG. 5A before interruptionis restarted.

FIG. 6 is a flow chart of the communication routine of the MCU 21 calledin step #505 in FIG. 5A, and corresponds to the communication routine inFIG. 4 of the camera 1.

In step #601, in order to transmit the data back flag information fromthe high-performance data back 20, data in the memory DM(1) of the MCU21 is transmitted to a serial register DSR (not shown) of the MCU 21.

In step #602, the terminal Q12 is set at L level to inform to the camera1 that the transmission preparation is completed. Note that in step#503, the terminal P12 is already set at L level, and even if theterminal P12 goes to H level thereafter, the terminal P12 can be held atL level as long as the terminal Q12 is set at L level. In step #603,processing is repeated until a serial flag is set to be 1. The serialflag is set to be 0 when each byte (8 bits) data begins to be exchanged,and becomes 1 every time eight serial clock pulses from the MCU 10 arecounted. When this flag is set to be 1, this means that 1-byte datatransmission is completed. When eight serial clock pulses are input fromthe camera 1, the serial flag is set to be 1, and serial communicationof 1-byte data is completed. The flow then advances to step #604. Instep #604, the terminal Q12 is set at H level to indicate that the1-byte communication is completed.

In step #605, the memory pointer N of the memory DM(N) which stores datareceived from the camera 1 is set to be 2. Thereafter, in step #606, theterminal Q12 is set at L level to inform to the camera 1 that receptionpreparation is completed. In step #607, processing is repeated until theserial communication is completed as in step #603, i.e., theabove-mentioned serial flag is set to be 1. Subsequently, in step #608,the data transmitted to the serial register DSR of the MCU 21 is storedin the memory DM(N) of the MCU 21. In step #609, the terminal Q12 is setat H level to indicate that 1-byte communication is completed. In step#610, the communication memory pointer N is incremented by 1. If Nincremented by 1 is equal to or smaller than 5, the flow returns to step#606, and 3- and subsequent byte data are received. If N exceeds 5, theflow returns to the main routine, thus completing this subroutine. Theflow then advances to step #507 in FIG. 5A.

FIG. 7 is a flow chart of the printing routine of the MCU 21 called instep #506 in FIG. 5A.

In step #701, a terminal Q16 is set at L level to turn on a transistorTr1, thereby turning on the printing lamp 26. In step #702, it is waiteduntil the printing time tq elapses, and the flow then advances to step#703. In step #703, the terminal Q16 is set at H level to turn off thetransistor Tr1, thereby turning off the printing lamp 26. Thus, thissubroutine is ended. In this manner, the data printing operation iscompleted.

FIG. 8 is a timing chart of communication between the camera 1 and thehigh-performance data back 20. The operations shown in the flow chartsof FIGS. 4 to 6 will be described below with reference to FIG. 8.

When the MCU 10 activates the terminal P12 at time t=tc1 in step #101,the MCU 21 detects this activating signal in step #503 in the loop ofstep #502, step #503, step #504, step #507, step #508, and step #502,and the flow advances from step #503 to step #505 to execute thecommunication routine shown in FIG. 6.

The MCU 21 transmits the 1st-byte data DM(1) (=data back flaginformation) to the serial register DSR of the MCU 21 in step #601 inFIG. 6, and sets the terminal Q12 at L level in step #602 (t=tc2). TheMCU 10 is then apt to set the terminal P12 at H level at time t=tc3. Theflow then advances to step #102 to check if the terminal P12 is at Llevel. Since the states of the terminals when the terminals P12 and Q12are connected through the contacts 1c and 20c are kept at L level underthe influence of the terminal Q12, as shown in FIG. 8D, the flowadvances from step #102 to step #103, and the MCU 10 starts transmissionof the serial clock to the MCU 21 (FIG. 8E). Since a terminal P13 isconnected to a serial clock terminal Q13 of the MCU 21 through thecontacts 1d and 20d, the data back flag information (1st byte) is outputfrom a serial output terminal Q15 of the MCU 21 in synchronism with thisclock. The 1st-byte information $81 (10000001 in binary notation) isoutput bit by bit from its LSB (least significant bit). This output istransmitted to a serial input terminal P15 of the MCU 10 through thecontact 20f of the data back 20 and the contact 1f of the camera 1, andis transmitted bit by bit to the serial register SR of the MCU 10 insynchronism with the serial clock. When eight clock pulses are outputfrom the terminal P13 (t=tc4), 1-byte data transmission is completed.The serial flag of the MCU 21 is set to be 1, and the flow advances fromstep #603 to step #604 to set the terminal Q12 at H level (t=tc5). Instep #605, the memory pointer N is set to be 2, and in step #606, theterminal Q12 is set at L level (t=tc6). In step #607, the serial flag istemporarily set to be 0, and it is then waited until the flag becomes 1.

Meanwhile, the MCU 10 waits for the lapse of a predetermined period oftime (a total of a time required until 1st-byte signal transmission iscompleted and a time required until the MCU 21 of the data back 21 isready for receiving the 2nd-byte data) in step #104 until the MCU 21 isready for reception. In this case, a change L→H→L in terminal Q12 can bemonitored to assure proper operation and to shorten required time. Whenthe flow advances from step #104 to step #105, the data back flaginformation transmitted to the serial register SR is transmitted to thememory M(1) of the MCU 10. In step #107, the memory pointer N is set tobe 2, and data stored in the memory M(N) indicated by the memory pointeris transmitted to the serial register SR of the MCU 10. Since N=2 isinitially set, film sensitivity data of a 2nd byte is transmitted to theserial register SR. In step #109, transmission of the serial clock fromthe MCU 10 to the MCU 21 is started (t=tc7). In step #110, it is waiteduntil transmission of the serial clock is completed and the data back isready for receiving the next data. If the film sensitivity is ISO100(SV=5), 00000101 in binary notation is output from a serial clockterminal P14 of the MCU 10 in synchronism with the clock. When eightclock pulses are output (t=tc8), transmission of 1-byte data iscompleted. The serial flag of the MCU 21 is then set to be 1, and theflow advances from step #607 to step #608. The data transmitted to theserial register DSR of the MCU 21 is transmitted to the memory DM(N) ofthe MCU 21. Since N=2 is initially set, the film sensitivity informationis stored in the memory DM(2) of the MCU 21. Subsequently, in step #609,the terminal Q12 is set at H level (t=tc9). In step #610, the memorypointer N is incremented by 1. If N exceeds 5, the flow returns to themain routine. In this case, since "2" is updated to "3", the flowreturns to step #108, and 3rd-byte data is awaited. On the other hand,the MCU 10 waits for the lapse of a predetermined period of time in step#110, and in step #111, updates the memory pointer N by 1. If N exceeds5, the flow returns to the main routine. However, in this case, since"2" is updated to "3", the 3rd-byte data is transmitted. Steps #108 to#111 and steps #606 to #610 are repeated until N=5. When 5-byte data aretransmitted and received, the MCUs 10 and 21 return from thecorresponding communication routines, and the series of communicationoperations are completed.

FIG. 9 is a timing chart after the release operation when the camera 1and the high-performance data back 20 are combined. Before the releaseoperation, the printing flag PRNF is 0, and the interruption routine inFIG. 3 advances from step #41→step #42→return. When the release button(not shown) of the camera 1 is depressed and the release switch SW1 isturned on, an input terminal P10 of the MCU 10 is changed from H to Llevel (t=t0). In step #42, this change is detected, and the flowadvances to step #43. Thus, the release sequence shown in FIG. 9 isstarted.

In step #43, the terminal P11 is set at L level to generate the printingsignal to the MCU 21 (t=t1). In step #504 in the loop of steps #502 to#508, the MCU 21 detects that terminal Q11 connected to the terminal P11through the contacts 1b and 20b goes to L level. The flow then advancesto step #506, and the printing routine shown in FIG. 7 is executed.

When the printing routine shown in FIG. 7 is executed, the MCU 21 setsthe output terminal Q16 at L level in step #701 (t=t2). The transistorTr1 is then turned on and the printing lamp 26 is turned on. Datadisplayed on the printing LCD in step #508 is projected onto a film (notshown), thus starting the printing operation. The MCU 21 measures thetime tq required for the printing operation in step #702, and the flowthen advances to step #703. In step #703, the terminal Q16 is set at Hlevel to turn off the transistor Tr1, so that the printing operation forthe printing time tq is completed. In this manner, the printing routineis ended.

The MCU 10 sets the printing flag PRNF to be 1 in step #44 after step#43 and resets its internal timer. The flow then jumps to step #10 inthe main routine shown in FIG. 2. In step #10, a stack is cleared, andin step #11, the sequence-activator is activated In step #12, diaphragmcontrol is performed Since interruption is kept enabled during executionof these steps, the interruption processing routine shown in FIG. 3 isexecuted at every predetermined time interval (e.g., 2 ms describedabove). However, since the printing flag PRNF is 1, the flow advancesfrom step #41 to step #45. In step #45, the lapse time t after the timeris reset in step #44 is compared with the predetermined printing signaltransmission time tp. Processing of step #41→step #45→return is repeatedfor a while parallel to the diaphragm control. When the lapsed time tafter the timer is reset exceeds the predetermined time tp, the flowadvances from step #45 to step #46, and the printing signal terminal P11is set at H level (indicating completion of the printing signal). Instep #47, the printing flag PRNF is set to be 0. In step #48,interruption is forbidden, and the flow then returns. Thereafter, theinterruption processing routine in FIG. 3 is not executed untilinterruption is enabled in step #9. When the diaphragm control iscompleted in step #12, the shutter control is executed in step #13, andthe mirror-down, shutter-charging, and film-feeding routine is executedin step #14. Upon completion of step #14, the flow jumps to step #1, andthe routine from step #1 described above is executed again.

As has been described, when the high-performance data back 20 ismounted, the bit "7" of the data back flag information (=M(1)) is 1.Therefore, the flow advances from step #6 to step #8 in the main routineof FIG. 2, and the printing signal transmission time tp is set to be 10ms. This transmission time is shorter than tq=20 ms to 60 ms set by theMCU 21, as depicted in FIG. 9, and the printing operation is performedfor the printing time tq set by the MCU 21. If the printing signaltransmission time tp were longer than the printing time tq, the dataprinting operation would be performed again after the flow advances tostep #507→step #508→step #502→step #503→step #504 after the printingoperation is completed in step #506. In this embodiment, such anoperation is never performed. The printing time set by the camera 1becomes longer than the printing time set by the high-performance databack 20 when a sensitivity is preferably set to be lower than a ratedsensitivity according to characteristics of an emulsion of a film to besubjected to printing, i.e., when the film sensitivity selection isswitched from an automatic mode to a manual mode. Since the data backperforms exposure from the rear surface side of a film, such situationoccurs. FIG. 11 is a block diagram showing a combination of a simplifieddata back 30 and the camera 1.

The camera 1 is the same as that in the embodiment shown in FIG. 1, anda data back is replaced with a data back 30 of a simplified type.Contacts 30a and 30b of the simplified data back 30 are connected to thecontacts 1a and 1b of the camera 1, and only a printing signal istransmitted through these contacts. The simplified data back 30 also hasan MCU 31. However, the MCU 31 has a simpler function than that of theMCU 21 of the high-performance data back 20. Since the MCU 31 has nofunction of serial communication with the camera 1, a printing operationon the basis of data from the camera 1 cannot be performed. However, abasic operation as a data back such as a printing operation of "year,month, and day" data and "hour, minute, and second" data can beperformed. A mode selector 32, an information-setting device 33, adisplay LCD 34, and a data-printing LCD 35 respectively correspond tothe mode selector 22, the information-setting device 23, the display LCD24, and the data-printing LCD 25 but have simplified functions. Theprinting signal from the camera 1 is received at the contact 30b, and isdirectly supplied to the base of a transistor Tr1. An ON/OFF operationof a printing lamp 36 is controlled by an ON/OFF operation of thetransistor Tr1. Since a printing time is automatically changed inaccordance with a film sensitivity set at the camera 1, setting of afilm sensitivity at the data back is not required.

FIG. 12 is a timing chart when communication is attempted between thecamera 1 and the simplified data back 30.

When the MCU 10 activates the terminal P12 at time t=tc1 in step #101,since the MCU 31 has neither a communication function nor acommunication terminal, it does not influence the terminal P12.Therefore, the MCU 10 sets the terminal P12 at H level at t=tc3, and theflow advances to step #102 to check if the terminal P12 is at L level.Unlike in FIG. 9, since the terminal P12 is at H level, the flowadvances to step #106. In step #106, the data back flag memory M(1) iscleared to 0, and the MCU 10 returns from the communication routine,thus completing a series of communication routine. In this case, data"0" is stored as the data back flag M(1). More specifically, a messageindicating that communication cannot be performed with the data back isstored in the memory.

When the flow advances from step #5 to step #6 in the main routine ofFIG. 2, the memory M(1) is cleared, and the bit "7" is 0, and hence, theflow advances to step #7. In step #7, a time of 20 ms to 60 ms is set asthe printing time tp on the basis of the film sensitivity SV set at thecamera 1, and interruption is enabled in step #9.

FIG. 13 is a timing chart after the release operation when the camera 1and the simplified data back 30 are combined. Before the releaseoperation, the printing flag PRNF is 0, and the interruption routineshown in FIG. 3 advances to step #41→step #42→return. When the releasebutton (not shown) of the camera 1 is depressed and the release switchSW1 is turned on, the input terminal P10 of the MCU 10 is changed from Hto L level (t=t0). This change is detected in step #42, and the flowadvances to step #43, thus starting the release sequence shown in FIG.13.

In step #43, the terminal P11 is set at L level to generate the printingsignal to the simplified data back 30 (t=t1). The transistor Tr1 whosebase is connected to the terminal P11 through the contacts 1b and 30b isthen turned on, and the printing lamp 36 is turned on. Data displayed onthe data-printing LCD 35 by the MCU 31 is projected onto a film (notshown), thus starting the printing operation.

Meanwhile, the MCU 10 sets the printing flag PRNF in step #44 after step#43, and resets the timer for measuring the transmission time. The flowthen jumps to step #10 in the main routine of FIG. 2. In step #10, astack is cleared. In step #11, the sequence-activating routine isexecuted. In step #12, the diaphragm-controlling routine is executed.During execution of these steps, since the interruption is kept enabled,the interruption processing routine shown in FIG. 3 is executed atpredetermined time intervals. However, since the printing flag PRNF is1, the flow advances from step #41 to step #45. In step #45, the time tmeasured by the timer for measuring the printing signal transmissiontime is compared to the predetermined transmission time tp which changesaccording to a film sensitivity. Processing of step #41→step #45→returnis repeated for a while parallel to the diaphragm control. When the timet measured by the timer exceeds the predetermined time tp, the flowadvances from step #45 to step #46, and the printing signal terminal P11is set at H level. In step #47, the printing flag PRNF is set to be 0.In step #48, the interruption is forbidden, and the flow then returns tothe main routine. Thereafter, the interruption processing routine shownin FIG. 3 is not executed until the interruption is enabled in step #9.When the diaphragm control is completed in step #12, the shutter controlis executed in step #13. In step #14, the shutter-charging andfilm-feeding routine is executed. Upon completion of step #14, the flowjumps to step #1, and the routine after step #1 is restarted.

In FIG. 13, the printing signal transmission time set at the camera 1 isused as the printing time tp, and the data printing operation isperformed according to this printing time tp. Since the printing time tpchanges within the range of 20 ms to 60 ms according to a filmsensitivity, the data back need not perform setting. However, when theprinting time is to be manually changed like in the high-performancedata back, the time is left unchanged.

According to the first embodiment of the present invention, a data backhaving a communication function can be discriminated from a data backhaving no communication function, and a printing signal transmissiontime suitable for the discriminated data back is set in the data back,thus allowing optimal control.

(2) Second Embodiment

A camera and an accessory according to a second embodiment have the samestructures as those of the camera and the accessory shown in FIG. 1. Thecontents of programs set in microcomputers (MCUs) 10 and 21 of thecamera and the accessory according to the second embodiment aredifferent from those in the first embodiment.

FIG. 14 is a flow chart of a main routine of the MCU 10. Step #1000 is apreset routine executed only immediately after a reset operation. Inthis routine, interruption for release (or release interruption) isforbidden, and a flag DBINIF indicating that communication with a databack is not yet performed is set to be 1. In step #1001, a photometryroutine is executed, so that an A/D-converted value of a photometricoutput from a photometer 2 is read. In step #1002, aninformation-setting routine is executed, so that an exposure controlmode, a DX code on a patrone, various information of a lens, a presetshutter speed, and the like are read from an information-setting device3. In step #1003, an apex-calculating routine is executed, so that acalculation is performed on the basis of information read in steps #1001and #1002 to obtain a shutter speed and a diaphragm value for displayand control. In step #1004, a display routine is executed to drive adisplay 4, thus performing a predetermined display. It is then checkedin step #1005 if the flag DBINIF is 0. The flag DBINIF is 1 immediatelyafter the reset operation. Thus, a communication routine in step #1007is executed, and the flow advances to step # 1009. Once a cameracommunicates with data back 20, the flag DBINIF is set to be 0. Thus,the flow advances from step #1005 to step #1006 to check if a flagEXPF=1. If YES in step #1006, the flow advances to step #1007, and thecommunication routine is executed in step #1007. However, if NO in step#1006, the flow advances to step #1008, and the release interruption isenabled. Thereafter, the communication routine is executed in step#1007. The release interruption is enabled in step #1009 after step#1007 since the flow may advance to step #1007 without going throughstep #1008. When the flag DBINIF is 1, since no communication has beenexecuted with the data back 20, communication must be executed beforethe release interruption is enabled. Once the communication is executed,the flag DBINIF is always 0 even immediately after the releaseoperation. Thus, whether or not the release interruption is enabled canbe determined on the basis of the flag EXPF. In an exposure valueprinting mode, new display data is required after the photometry routineis executed following a release operation. Therefore, the data back 20sets the flag EXPF=1 so that the release interruption is enabled afterthe communication. After step #1009, the flow returns to step #1001.After the release operation, when the release routine is completed, theflow jumps to step #1010. In step #1010, a stack is cleared, andinterruption is forbidden in order to set the same state as that afterthe processing in step #1000. Thereafter, processing is restarted fromthe photometry routine in step #1001.

FIG. 15 is a flow chart of the release interruption routine. After theinterruption is enabled, this routine is executed at predetermined timeintervals (e.g., 2 ms). Immediately after power-on, interruption isforbidden, and can be executed after the release interruption is enabledin step #1008 or #1009.

When this routine is executed, it is checked in step #1040 if an inputterminal P10 is set at L level. If YES in step #1040, the flow advancesto step #1041; otherwise, the flow returns to the main routine andprocessing before interruption processing is restarted. When a releasebutton is depressed and a release switch SW1 is turned on, the terminalP10 is set at L level, and the flow advances to step #1041. In step#1041, a terminal P11 is set at L level to generate to a printing signalto the data back 20. After the lapse of a time for allowing a responsefrom the data back 20, the terminal P11 is reset at H level. In step#1042, a sequence-activating routine is executed to activate asequence-activator 5, so that a magnet and the like are energized, thusstarting a mirror-up operation. A diaphragm-controlling routine in step#1043 is then executed. When a diaphragm of a lens is stopped down by apredetermined amount, a diaphragm stop magnet is energized to lock thediaphragm. In step #1044, a shutter-controlling routine is executed toobtain a predetermined shutter speed. In step #1045, a shutter-chargingand film-feeding routine is executed. Thereafter, the flow returns tostep #1010 in the main routine of FIG. 14, i.e., again to the photometryroutine after the mirror-down operation.

FIG. 16 is a flow chart of a communication routine of the MCU 10 whichis called as a subroutine in step #1007 in FIG. 14.

In step #1101, the terminal P12 is set at L level, and is then reset toH level after the lapse of a predetermined period of time. To set theterminal P12 at L level means to activate a mounted data back. If thedata back is mounted, a terminal Q12 connected to the terminal P12through contacts 1b and 20b goes to L level in response to theactivation. Even though the terminal P12 would be set at H level afterthe lapse of the predetermined period of time, it is kept at L level aslong as the terminal Q12 is at L level.

In step #1102, it is checked if an input to the terminal P12 is at Llevel. If NO in step #1102, the flow advances to step #1106; otherwise,the flow advances to step #1103. If the data back 20 is mounted, sincethe terminal P12 is set at L level, the flow advances to step #1103. Ifthe data back 20 is not mounted, the terminal P12 is set at H level, andthe flow advances to step #1106.

Thus, processing after step #1103 is executed when the data back 20 ismounted. In steps #1103 to #1105, processing for receiving 1st-byte databack flag information from the data back 20 is performed. In step #1103,a serial clock is started, and the lapse of a predetermined period oftime is waited in step #1104. More specifically, the lapse of a timeuntil a serial flag is set to be 1 to indicate completion oftransmission and storage of transmitted data in a memory of the databack 20 is waited. In step #1105, communication data supplied from thedata back 20 and stored in a serial register SR of the MCU 10 is storedin a memory M(1).

In steps #1107 to #1111, processing for transmitting 4-byte data fromthe camera 1 to the data back 20 is executed. In step #1107, N=2 is setas a memory pointer of transmission data. In step #1108, data in amemory M(N) of the MCU 10 is transmitted to the serial register SR. Instep #1109, a serial clock is started. In step #1110, the lapse of apredetermined period of time is waited until the serial transmission iscompleted. That is, the lapse of a time until the serial flag is set tobe 1 to indicate completion of reception of the data by the data back 20is waited. In step #1111, a memory pointer N is incremented by 1. If Nexceeds 5, the flow advances to step #1112. If N is equal to or smallerthan 5, the flow returns to step #1108. After the 1st-byte data istransmitted, since N=3, the flow returns to step #1108, and processingin steps #1108 to #1111 is repeated. After 4th-byte data is transmitted,since N=6 in step #1111, the flow then advances to step #1112.

Step #1112 is executed after step #1106 or #1111. In step #1112, theflag DBINIF indicating that communication is performed once is set to be0, thus ending the communication subroutine shown in FIG. 16.

FIG. 17A is a flow chart of a main routine of the MCU 21 stored in thedata back 20. In step #1501, a preset operation after a battery isinserted is performed. In general, after the power switch of the camera1 is turned off, processing in steps #1502 to #1507 is repeated. In step#1502, an information-setting routine is called as a subroutine, so thatsetting of a printing mode is read from a mode selector 22 or data to beprinted is corrected according to information from theinformation-setting device 23.

It is checked in step #1503 if the terminal Q12 is at L level. If YES instep #1503, the flow advances to step #1505; otherwise, the flowadvances to step #1504. The terminal Q12 is set at L level when thecamera 1 activates communication to set the terminal P12 at L level. Inthis case, the flow advances to step #1505 to call the communicationroutine shown in FIG. 18, thus exchanging data with the camera 1. If thecamera 1 does not activate communication, the terminal Q12 is kept at Hlevel, and the flow advances to step #1504. It is checked in step #1504if the terminal Q11 is at L level. If NO in step #1504, the flowadvances to step #1507. The terminal Q11 is set at L level when thecamera 1 executes the release routine and sets the terminal P11 toactivate the printing operation. In this case, the MCU 21 calls theprinting routine shown in FIG. 19 in step #1506, and performs printingof predetermined data. Step #1507 is executed after steps #1504 to#1506, so that data set in step #1502, data obtained by communication instep #1505, and data which changes after the printing operation in step#1506 are displayed. Upon completion of the processing in step #1507,the flow returns to step #1502, and the above-mentioned processing isrepeated.

FIG. 17B is a flow chart of an interruption routine of the MCU 21 storedin the data back 20. This routine is activated every minute by aninterruption of a timer incorporated in the MCU 21, and "year, month,day, hour, and minute" data are counted up.

FIG. 18 is a flow chart of the communication routine of the MCU 21called in step #1505 in FIG. 17A, and corresponds to the communicationroutine of the camera shown in FIG. 16.

In step #1601, in order to transmit data back flag information from thedata back 20, data in a memory DM(1) of the MCU 21 is transmitted to aserial register DSR of the MCU 21.

In step #1602, the terminal Q12 is set at L level to inform to thecamera 1 that transmission preparation is completed. In step #1603,processing is repeated until the serial flag becomes 1. When eightserial clock pulses are input from the camera 1, the serial flag is setto be 1 (serial communication is completed), and the flow advances tostep #1604. In step #1604, the terminal Q12 is set at H level toindicate that 1-byte communication is completed.

In step #1605, "2" is set as the memory pointer N of a memory storingdata to be transmitted to the camera 1. In step #1606, the terminal Q12is set at L level to inform to the camera 1 that reception preparationis completed. In step #1607, processing is repeated until serialcommunication is completed as in step #1603. In step #1608, datatransmitted to the serial register DSR of the MCU 21 is stored in amemory DM(N) of the MCU 21. In step #1609, the terminal Q12 is set at Hlevel to indicate that 1-byte communication is completed. In step #1610,the communication memory pointer N is incremented by 1. If N exceeds 5,the flow returns to end this subroutine. If N is equal to or smallerthan 5, the flow returns to step #1606.

FIG. 19 is a flow chart of the printing routine of the MCU 21 called instep #1506 in FIG. 17A.

In step #1701, a terminal Q16 is set at L level to turn on a transistorTr1, thus turning on a printing lamp 26. In step #1702, the lapse of aprinting time tp is waited, and the flow then advances to step #1703. Instep #1703, the terminal Q16 is set at H level to turn off thetransistor Tr1, thereby turning off the printing lamp 26. Subsequently,in step #1704, the content of a memory DM(3) for storing frame countdata for the printing operation is incremented by one, and thissubroutine is ended.

FIG. 20 is a timing chart of communication between the camera 1 and thedata back 20. The operations shown in the flow charts of FIGS. 16 to 18will be described below with reference to FIG. 20.

When the MCU 10 activates the terminal P12 at time t=tc1 in step #1101,the MCU 21 detects this activating signal in step #1503 in the loop ofstep #1502, step #1503, step #1504, step #1507, and step #1502, and theflow advances from step #1503 to step #1505 to execute the communicationroutine shown in FIG. 18.

The MCU 21 transmits the 1st-byte data DM(1) (=data back flaginformation) to the serial register of the MCU 21 in step #1601 in FIG.18, and sets the terminal Q12 at L level in step #1602 (t=tc2). The MCU10 sets the terminal P12 at H level at time t=tc3. The flow thenadvances to step #1102 to check if the terminal P12 is at L level. Thestates of the terminals when the terminals P12 and Q12 are connectedthrough the contacts 1c and 20c are kept at L level under the influenceof the terminal Q12, as shown in FIG. 20D. The flow advances from step#1102 to #1103, and transmission of the serial clock is started (FIG.20E). Since a terminal P13 is connected to a serial clock terminal Q13of the MCU 21 through contacts 1d and 20d, the 1st-byte data back flaginformation is output bit by bit from its LSB from a serial outputterminal Q15 of the MCU 21 in synchronism with this clock. This outputis transmitted to a serial input terminal P15 of the MCU 10 through thecontact 20f of the data back 20 and the contact 1f of the camera 1, andis transmitted bit by bit to the serial register SR of the MCU 10 insynchronism with the serial clock. When eight clock pulses are outputfrom the terminal P13 (t=tc4), 1-byte data transmission is completed.The serial flag of the MCU 21 is set to be 1, and the flow advances fromstep #1603 to step #1604 to set the terminal Q12 at H level (t=tc5). Instep #1605, the memory pointer N is set to be 2, and in step #1606, theterminal Q12 is set at L level (t=tc6). In step #1607, it is then waiteduntil the flag becomes 1.

Meanwhile, the MCU 10 waits for the lapse of a predetermined period oftime in step #1104 until the MCU 21 is ready. In this case, a changeL→H→L in terminal Q12 can be monitored to assure proper operation and toshorten required time. The flow advances from step #1104 to step #1105,and the data back flag information transmitted to the serial register SRis transmitted to a memory M(1) of the MCU 10. In step #1107, the memorypointer N is set to be 2, and data stored in the memory M(N) indicatedby the memory pointer is transmitted to the serial register SR of theMCU 10. Since N=2 is initially set, film sensitivity data of a 2nd byteis transmitted to the serial register SR. In step #1109, transmission ofthe serial clock is started (t=tc7). In step #1110, it is waited untilserial transmission is completed. If the film sensitivity is IS0100(SV=5), 00000101 in binary notation is output from its LSB from a serialclock terminal P14 of the MCU 10 in synchronism with the clock. Wheneight clock pulses are output (t=tc8), transmission of 1-byte data iscompleted. The serial flag of the MCU 21 is then set to be 1, and theflow advances from step #1607 to step #1608. The data transmitted to theserial register DSR of the MCU 21 is transmitted to the memory DM(N) ofthe MCU 21. Since N=2 is initially set, the film sensitivity informationis stored in a memory DM(2) of the MCU 21. Subsequently, in step #1609,the terminal Q12 is set at H level (t=tc9). In step #1610, the memorypointer N is incremented by 1. If exceeds 5, the flow returns to themain routine. In this case, since "2" is updated to "3", the flowreturns to step #1108, and 3rd-byte data is awaited. On the other hand,the MCU 10 waits for the lapse of a predetermined period of time in step#1110, and in step #1111, increments the memory pointer N by 1. If Nexceeds 5, the flow returns to the main routine. However, in this case,since "2" is updated to "3", the flow returns to step #1108. Thus, the3rd-byte data is transmitted. Steps #1108 to #1111 and steps #1606 to#1610 are repeated until N=5. Upon completion of transmission/receptionof a total of 5-byte data, the flow advances to step #1112, and the MCU10 sets the flag DBINIF to be 0. The MCU 21 returns to the main routine,and the series of communication operations are completed.

FIGS. 21A and 21B are timing charts of the release sequence. When arelease button (not shown) of the camera 1 is depressed and the releaseswitch SW1 is turned on, an input terminal P10 of the MCU 10 goes from Hto L level, and this change is detected in step #1040 in FIG. 15 duringinterruption executed at predetermined time intervals. The flow thenadvances to step #1041, thus starting the release sequence in FIG. 15(t=t0).

FIG. 21A is a timing chart when an exposure value is printed. In step#1041, the terminal P11 is set at L level for a predetermined period oftime, thus generating a printing signal to the MCU 21 (t=t1). The MCU 21detects that the terminal Q11 connected to the terminal P11 through thecontacts 1b and 20b goes to L level in step #1504 in the loop of steps#1502 to #1507. The flow then advances to step #1506, and the printingroutine shown in FIG. 19 is executed.

When the printing routine shown in FIG. 19 is executed, the MCU 21 setsthe output terminal Q16 at L level in step #1701 (t=t2). The transistorTr1 is turned on, and the printing lamp 26 is turned on. Thus, datadisplayed on the display LCD in step #1507 is projected onto a film (notshown), thus starting a printing operation. The MCU 21 measures a timetp required for the printing operation in step #1702, and the flowadvances to step #1703. In step #1703, the terminal Q16 is set at Hlevel to turn off the transistor Tr1, thus completing the printingoperation (t=t3)/ Subsequently, in step #1704, the content of a memoryDM(3) for storing a film frame count is incremented by one, and the flowreturns to end the printing routine. The flow then advances from step#1506 to step #1507 in FIG. 17 to display data.

Meanwhile, the MCU 10 activates the sequence-activator in step #1042after step #1041, and performs diaphragm control in step #1043. In step#1044, the shutter control is performed. In step #1045, theshutter-charging an film-feeding control is performed. Upon completionof step #1045, the flow returns to the main routine. The flow then jumpsto step #1010 in the main routine of FIG. 14. In step #1010, a stackpointer is cleared, and the routine from step #1001 is executed. In step#1001, the photometry routine after the mirror-down operation isexecuted again. In step #1002, the information-setting routine isperformed. In step #1003, the apex-calculating routine is executed. Instep #1004, information is displayed. In step #1005, since the flagDBINIF is already set to be 0, the flow advances to step #1006. If it isdetermined in step #1006 that the flag EXPF of the data back flaginformation is 1, the flow advances to step #1007, and the communicationroutine is executed (t=t4). Upon completion of the communication (t=t5),the flow advances to step #1009, and the release interruption isenabled. The interruption routine shown in FIG. 15 is executed atpredetermined time intervals. If the release button is kept depressed,processing from step #1041 is again executed (t=t6). After thecommunication routine, the flow advances from step #1501 to step #1507,the MCU 21 allows a display on the basis of data after the secondphotometry routine in the exposure value printing mode. The flowadvances from step #1502→step #1503→step #1504→step #1506, and aprinting operation of a second frame is allowed (t=t7).

FIG. 21B is a timing chart when an exposure value is not printed. Theprocessing content up to step #1004 in the main routine after aphotographing operation of a first frame is performed is the same asthat in FIG. 21A. In step #1005, since the flag DBINIF is already set tobe 0, the flow advances to step #1006. Since it is determined in step#1006 that the flag EXPF of the data back flag information is 0, theflow advances to step #1008, and the release interruption is enabled.The interruption routine shown in FIG. 15 is executed at predeterminedtime intervals. If the release button is kept depressed, the processingfrom step #1041 is executed without executing the communication routine(t=t6). In the exposure value non-printing mode, a printing operation of"year, month, day, hour, and minute" data as a basic function of thedata back can be performed since these data are stored in the MCU 21. Inaddition, this mode may be combined with a film frame count printingmode, even though the release routine is executed without executing thecommunication routine. More particularly, since the frame count data isupdated by the data back at step #1704, the MCU 21 can print the updateddata directly.

According to the second embodiment, when the data back is used in abasic manner, transmission of data from the camera to the data back isomitted. Therefore, a frame speed in a continuous photographing mode canbe increased.

When a film frame count is printed, a signal generated every time theframe is photographed in a camera is received and film frame count datais incremented by one. Therefore, the printing operation of the framecount can be performed with data transmission being omitted. When thefilm frame count data is received from the camera, the film frame countdata stored in the data back is replaced with the received data.Therefore, if data in the data back includes an error, the error is notaccumulated.

(3) Third Embodiment

FIG. 22 shows an outer appearance of a camera 101 according to a thirdembodiment of the present invention and a data back 202 mounted thereon.The data back 102 has a data printing section for printing data on afilm loaded in a portion (not shown) of the camera, so that an opticaldata printing operation is performed using a lamp or an LED. An LCD 103is arranged to confirm data to be printed. A user can monitor a settingcondition using a printing data display section (to be referred to as adata section hereinafter) 105, a film sensitivity display section (to bereferred to as a sensitivity section hereinafter) 106, and a dataprinting setting display section (to be referred to as a setting sectionhereinafter) 104.

The data section 105 displays data to be printed, and a numerical value(a maximum of six digits) such as a simple serial number, and the likecan be arbitrarily set by an operation button (not shown).

The sensitivity section 106 displays a symbol mark according to an ISOsensitivity of a film presently loaded in the camera. When a film ofIS0100 is loaded, "M" is displayed. When a high-sensitivity film isused, "H" is displayed, and when a low-sensitivity film is used, "L" isdisplayed. These marks may be selected by automatically detecting thesensitivity using a DX code of a film or manually setting with theabove-mentioned operation switch.

The setting section 104 displays whether or not a data printingoperation is performed. When the data printing operation is performed,"PRINT" is displayed, as shown in FIG. 22; otherwise, nothing isdisplayed. Selection of these can also be arbitrarily set by theabove-mentioned operation button. FIG. 23 is a block diagram of internalcircuits of the camera 101 and the data back 102 shown in FIG. 22.

A data-setting means 107 has a function of setting data to be printed,e.g., year, month, and day data, numerical value data, and the like,outputs the set data to a printing means 113 through a line (not shown),and outputs a time signal necessary for a printing operation accordingto the number of digits of set data, and the like to a time-calculatingmeans 111, as shown in FIG. 23. A parameter according to the number ofdigits of data is required since the printing operation is performed bya dynamic drive method in units of digits.

A sensitivity-setting means 108 sets a film sensitivity of a film used,and outputs an identification signal according to the sensitivity to thetime-calculating means 111, as shown in FIG. 23.

A setting means 109 for printing sets whether or not a data printingoperation is performed, and outputs a signal indicating that theprinting operation is performed or not to the time-calculating means111, as shown in FIG. 23.

The time-calculating means 111 calculates a time suitable for a printingoperation using the three input signals according to the type of dataand the film sensitivity, and outputs it as a printing time signal to afirst timer means 112. As the number of digits by the data-setting means107 is increased, or as the sensitivity set by the sensitivity-settingmeans 108 becomes lower, the time-calculating means 111 sets a signalhaving a longer printing time.

When the setting means 109 sets that the data printing operation is notperformed, the time-calculating means 111 outputs "0" to the first timermeans 112.

A release means 110 starts the operation of the camera upon depressionof a button, and outputs a release signal to the first timer means 112and a second timer means 115.

The first timer means 112 measures a time set by the above-mentionedprinting time signal in response to the input release signal as a startsignal.

Since the first timer means 112 outputs a printing signal to theprinting means 113 in response to the input release signal until timemeasurement is completed, the above-mentioned lamp or LED is turned onto perform a data printing operation during this interval.

On the other hand, when the release signal from the release means 110 isinput, the second timer means 115 activates an exposing means 114, i.e.,a device for driving a shutter, and sets the shutter in an open stateuntil time measurement based on a shutter time preset in the secondtimer means 115 by other means (not shown) is completed. As a result, anobject image is exposed on a film.

After the first and second timer means 112 and 115 completepredetermined time measurements, they output first and second completionsignals 118 and 119 to an AND gate 116.

When the AND gate 116 receives both the first completion signal 118,i.e., a printing completion signal, and the second completion signal119, i.e., an exposure completion signal, it outputs a winding signal toa winding means 117.

In response to the winding signal, the winding means 117 performs apredetermined operation to prepare for the next photographing operationas well as a winding operation of a film.

With the above-mentioned arrangement, data printing, shutter time, andfilm winding timings are controlled as follows.

When a printing time is shorter than the shutter time, the firstcompletion signal 118 from the first timer means 112 is output, andthen, the exposure completion signal 119 from the second timer means 115is output. Therefore, the winding means 117 is operated after the lattersignal is input, i.e., the exposure by the shutter is completed.

On the other hand, when the printing time is longer than the shuttertime, the relationship between the completion signals 118 and 119 alongthe time base is reversed. Therefore, the winding means 117 is operatedafter the printing operation is completed.

When the setting means 119 sets that the printing operation is notperformed, the timer means 112 is set to be zero, and immediatelyoutputs the completion signal 118 in response to the input releasesignal. The winding means 117 is operated under the control of thecompletion signal 119 from the second timer means 115, i.e., completionof exposure.

FIGS. 24A and 24B are timing charts of the embodiment shown in FIG. 23.FIG. 24A shows a state wherein the printing time is shorter than theshutter time, and the operation of the winding means 117 is controlledby the second completion signal 119.

Conversely, FIG. 24B shows a state wherein the printing time is longerthan the shutter time and the operation of the winding means 117 iscontrolled by the first completion signal 118.

FIG. 26 shows a block diagram of a fourth embodiment of the presentinvention, which operates under the control of a CPU 125. FIGS. 25A to25E are operation flow charts of this embodiment, in which FIGS. 25A to25D show subroutines, and FIG. 25E shows a main routine. The operationsof the subroutines will be described below.

FIG. 25A shows a data-setting routine. In step #2001, set printing datais stored in a memory. In step #2002, the number of digits of the setdata is stored in a memory as a value n. The above steps correspond tothe operation of the data-setting means 107 in FIG. 23.

FIG. 25B shows a sensitivity-setting routine. In step #2003, a selectedfilm sensitivity is stored in a memory. It is checked in step #2004 ifthe selected sensitivity is equal to or lower than ISO64, and if NO instep #2004, it is checked in step #2005 if the selected sensitivity isequal to or lower than ISO160.

If YES in step #2004, "4" is stored in a memory as a value α in step#2006; if NO in step #2004 and YES in step #2005, "2" is stored as α instep #2007; and if NO in step #2005, "1" is stored as α in step #2008.

In this embodiment, film sensitivities are classified into three ranks,with a ratio set to be 1 : 2 : 4. As will be described later, this ratiocan be used as a ratio of times necessary for printing operations atcorresponding film sensitivities. However, the film sensitivities may beclassified into a larger number of ranks or may be merely classifiedinto two ranks.

The above steps correspond to the operation of the sensitivity-settingmeans 108 in FIG. 23.

FIG. 25C shows a setting routine for printing. In step #2009, it ischecked whether or not a printing operation is performed. If YES in step#2009, the flow ends; otherwise, n is set to "0" as shown in FIG. 25C.In this case, the stored data "0" takes priority over the value n ofFIG. 25A. The above steps correspond to the operation of the settingmeans 109 in FIG. 23.

FIG. 25D shows a portion for calculating a time necessary for a printingoperation, called a T₁ calculating routine. In step #2011, the data nset in step #2002 in the data-setting routine is multiplied by α in oneof steps #2006 to #2008 from the sensitivity-setting routine. In step#2012, the product is stored in a memory as T₁. In general, T₁ is on theorder of ms, and in this embodiment, T₁ falls within the range ofseveral ms to several tens of ms. The above steps correspond to theoperation of the time-calculating means 111 in FIG. 23.

The main routine shown in FIG. 25E will be described below. Afterpower-on, a preset operation including a reset operation is performed instep #2013. In steps #2014 to #2017, the data-setting routine,sensitivity-setting routine, setting routine for printing, and T₁calculating routine described with reference to FIGS. 25A to 25D areexecuted.

In step #2018, a shutter time routine is executed, that is, the shuttertime is calculated by an apex calculation. The calculation result isstored in a memory as T₂.

In step #2019, various data are displayed on a display, such as the LCD103 shown in FIG. 22, on the basis of the calculation result.

The main routine includes step #2020 as a function of periodicallymonitoring generation of a release signal. When no release signal isgenerated, the flow returns to step #2014 and the above-mentionedroutines are executed.

When generation of the release signal is detected in step #2020, theshutter is opened in step #2021. In step #2022, measurement of T₂, i.e.,the shutter time, is started. The above operations correspond tofunctions of the release means 110, exposing means 114, and second timermeans 115 in FIG. 23.

In step #2023, data printing is started. In step #2024, measurement ofT₁, i.e., the printing time, is started. The above operations correspondto functions of the release means 110, printing means 113, and firsttimer means 112 in FIG. 23.

In step #2025, T₁ and T₂ are compared with each other.

If it is determined in step #2025 that T₁, i.e., the printing time isshorter, completion of measurement of T₁ is waited in step #2028. Uponcompletion of measurement, the printing operation is stopped in step#2029. The above steps correspond to the operations of the first timermeans 112 and the printing means 113 in FIG. 23.

Thereafter, T₂, i.e., the shutter time, is measured in step #2030. Uponcompletion of measurement, the shutter is closed in step #2031, and afilm winding operation is performed in step #2032. The flow returns tothe initial routine to prepare for the next release operation. The abovesteps correspond to the operations of the second timer means 115,exposing means 114, the AND gate 116, and the winding means 117 shown inFIG. 23, and FIG. 24A.

If it is determined in step #2025 that T₁ is longer, T₂ is measured instep #2026. Upon completion of measurement, the shutter is closed instep #2027. Thereafter, completion of measurement of T₁ is waited instep #2028, and the printing operation is stopped in step #2029.

In this routine, completion of measurement of T₂ is re-confirmed insteps #2030 and #2031. Since the measurement is completed in steps #2026and #2027, steps #2030 and #2031 are merely passed.

Thereafter, the film winding operation is performed in step #2032. Theabove steps correspond to the operations in FIG. 24B.

The flow returns to the initial routine, i.e., step #2014, and theoperations are repeated to prepare for the next release operation.

As described above, the flow of operation is such that the film windingoperation is performed after measurement of a longer one of T₁ and T₂ iscompleted, i.e., measurement of both T₁ and T₂ is completed.

When the shutter open operation timing and the printing start timingshown in steps #2021 and #2024 are greatly different from each other ortheir relationship is reversed, a shift term can be added to T₁ and T₂.

FIG. 26 is a block diagram of a camera using this embodiment.

A CPU 125 receives luminance information of an object from a photometer120 represented by SV, sensitivity information of a film used from afilm sensitivity-setting circuit 121 represented by SV, shutter timeinformation set by a shutter time setting circuit 122 represented by TV,diaphragm value information set by a diaphragm value setting circuit 123represented by AV, and various mode information set by switches andsequence information representing an operating condition of a camerafrom a condition detector 124 represented by SW. The CPU 125 performscalculations on the basis of various information, and causes a firstdriver 126 to drive an LED array 127 in association with a data backfunction. The LED array 127 has six digits of 7-segment LEDs for dataprinting. A method of printing data using lamps in an LCD isequivalently used in place of the method using the LED array 127.

A display 128 informs to a user photographing information or printingdata information using various display devices including the LCD 103.

Second and third drivers 129 and 130 drive a magnet 131 foropening/closing the shutter and a motor 132 for performing a filmwinding operation on the basis of the information from theabove-mentioned condition detector 124.

As described above, according to the third and fourth embodiments of thepresent invention, the film winding operation is performed after thedata printing operation is completed. Thus, data to be recorded can bereliably printed on a film, and the printing operation and the filmwinding operation are not simultaneously performed. Therefore, data canbe prevented from being blurred.

If the number of digits of printing data is set to be small or ahigh-sensitivity film is used, a printing time can be shortened, and afilm winding start timing need not be delayed. Therefore, a quickpreparation can be performed for the next exposure opportunity.

What is claimed is:
 1. A camera which can execute data communicationwith an attached accessory that can perform a data printing operationwherein data received from the camera is printed on a film surface,comprising:release means for generating a release signal for starting aphotographing operation; transmission means for transmitting data tosaid accessory during a time interval from the end of a photographingoperation to be beginning of a next photographing operation; and controlmeans for enabling the photographing operation after intervening datatransmission by said transmission means when said accessory is toperform said data printing operation, and for enabling the photographingoperation without intervening data transmission by said transmissionmeans when said accessory is not to perform said data printingoperation.
 2. A camera according to claim 1, wherein in response to areset operation, said control means enables the photographing operationonly after an intervening data transmission by said transmission means,regardless of whether said accessory is to perform said printingoperation.
 3. A camera according to claim 1, further comprising meansfor receiving from said accessory data indicating whether said accessoryis to perform said printing operation.
 4. A camera according to claim 1,wherein said transmission means transmits data relating to filmsensitivity, film frame count, shutter speed, and diaphragm value tosaid accessory.